RU2482115C2 - Method of producing epichlorohydrin using hydrogen peroxide and manganese complex - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing epichlorohydrin which is used as a solvent for cellulose, resins and dyes, as fumigant and as a structural unit when producing plastic, epoxy resins and phenol resins. The method involves reaction of allyl chloride with an oxidant in the presence of a catalyst which contains a water-soluble manganese complex in an aqueous reaction medium with molar ratio of allyl chloride to the oxidant ranging from 1:0.1 to 1:1.2, followed by removal of the epichlorohydrin product. Normally the catalyst contains a mononuclear manganese complex of general formula (I): [LMnX₃]Y (1) or a binuclear manganese complex of general formula (II): [LMn(|µ-X)₃MnL]Y₂ (II), where Mn is manganese; L or each L independently denotes a polydentate ligand; each X independently denotes coordination compounds and each µ-X independently denotes bridge coordination compounds selected from a group consisting of: RO^-, Cl^-, Br^-, I^-, F^-, NCS^-, N₃ ^-, I₃ ^-, NH₃, NR₃, RCOO^-, RSO₃ ^-, RSO₄ ^-, OH^-, O^2-, O₂ ^2-, HOO-, H₂O, SH^-, CN^-, OCN^-, and S₄ ^2- combinations thereof, where R is a C₁-C₂₀ radical selected from a group consisting of alkyl, cycloalkyl, aryl, benzyl and combinations thereof, and Y denotes an oxidation-stable counter-ion.

EFFECT: method enables to carry out the process with high selectivity and number of rotations.

15 cl, 4 ex, 3 tbl

Description

FIELD OF THE INVENTION

The present invention relates to a process for the preparation of epichlorohydrin (“ESN”) by the catalytic oxidation of allyl chloride (“AC”) using hydrogen peroxide and a manganese complex.

State of the art

ESN (also known as "EPI") is of significant interest. For example, it is used as a structural unit for the production of plastics, epoxies, phenolic resins and other polymers. It is used as a solvent for cellulose, resins and dyes, and it has been found to be used as a fumigant for insects. ESN can interact with water to form the corresponding diol.

Conventional methods for producing ESN include the use of chlorine-containing oxidizing agents, for example, HOC1. The disadvantage of this method is the relatively large number of side-formed salts of chlorides.

Despite significant interest in UST, a highly atomically efficient production method, not accompanied by the formation of side salts and / or other by-products, is not yet available. Moreover, an alternative preparation method is accompanied by adverse reactions and / or suffers from a difficulty in isolation. ESN is usually subjected to various stages of purification before it can be used for subsequent reactions.

For example, the method for producing UST in WO2004 / 048353 is carried out in a reaction medium containing at least 75 wt.% Organic material, which leads to significant release problems. Moreover, from this and other references that describe the synthesis of ESN, it is known that the product formed by these methods often contains both epichlorohydrin and various by-products resulting from the opening of the oxirane cycle, namely 1-chloro-3- methoxy-2-propanol, 1-chloro-2-methoxy-3-propanol, 3-chloro-1,3-propanediol and 1,3-dichloro-2-propanol.

From the foregoing, it follows that industry is still looking for a commercially feasible method for producing ESN with a high speed (TON) and high selectivity, which means there are no by-products, such as diols. This method also allows the use of an aqueous solvent as a reaction medium in order to avoid problems associated with environmental pollution and other problems associated with the use of acetonitrile and similar organic solvents. The present invention avoids these disadvantages.

SUMMARY OF THE INVENTION

Thus, the present invention provides a process for the preparation of epichlorohydrin ("ESN") by the catalytic oxidation of allyl chloride ("AC") with an oxidizing agent, wherein the catalytic oxidation is carried out in an aqueous reaction medium in which a water-soluble manganese complex is used as an oxidation catalyst, followed by isolation of epichlorohydrin.

In a preferred embodiment, the ESN or part of the ESN is isolated as an organic phase that contains an ESN or a mixture of allyl chloride and ESN. Moreover, two organic phases can be formed with different contents of AS and ESN and, therefore, with different densities.

The implementation of the invention

In accordance with the description, the expressions “epoxidation” and “oxidation” refer to the same reaction: the conversion of a double carbon - carbon bond of allyl chloride into an oxirane cycle. The invention will now be described in more detail.

It was unexpectedly discovered that the method can be used to obtain ESN with high selectivity in the absence of noticeable amounts of by-products (diols, etc.), despite the fact that the reaction is carried out in an aqueous reaction medium. As for water-soluble manganese complexes that can be used as oxidation catalysts, many suitable complexes are known. In this regard, it should be noted that the compound described in the invention is actually a catalyst precursor. Indeed, in all scientific sources and patent literature, the catalyst precursor is usually defined as an active compound, which during the reaction can be different and essentially can even change during the reaction that it catalyzes. For convenience, and as is customary in the literature, we consider the complex as if it were a catalyst.

Typically, the catalyst contains a manganese atom or several manganese atoms coordinated with a ligand or ligands. The manganese atom (s) can be in the oxidation state of II, III or IV and can be activated during the reaction. Of particular interest are the binuclear complexes of manganese. Suitable manganese complexes include mononuclear compounds of the general formula (I):

and binuclear compounds of the general formula (II):

,

NH₃, NR₃, RCOO^-,

,

, ОН^-, O^2-,

, HOO^-, H₂O, SH^-, CN^-, OCN^-, и

и их комбинаций, где R представляет собой радикал С₁-С₂₀, выбранный из группы, состоящей из алкила, циклоалкила, арила, бензила и их комбинаций, и Y представляет собой стабильный в отношении окисления противоион. Например, противоион Y может представлять собой анион, выбранный из группы, состоящей из RO^-, Сl^-, Вr^-, I^-, F^-,

RCOO^-,

ацетата, тозилата, трифлата (CF₃SO₃ ^-) и их комбинаций, причем R вновь представляет собой радикал С₁-С₂₀, выбранный из группы, состоящей из алкила, циклоалкила, арила, бензила и их комбинации. Тип аниона не очень критичен, хотя некоторые анионы являются более предпочтительными, чем другие. Предпочтительным противоионом является

. Лиганды, применимые для настоящего изобретения, представляют собой ациклические соединения, содержащие по меньшей мере 7 атомов в основной цепи или циклические соединения, содержащие по меньшей мере 9 атомов в цикле, причем каждый содержит атомы азота, разделенные по меньшей мере двумя атомами углерода. Предпочтительным классом лигандов является тот, который основан на (замещенном) триазациклононане ("Tacn"). Предпочтительным лигандом является 1,4,7-триметил-1,4,7,- триазациклононан ("TmTacn"), который является коммерчески доступным, например, от Aldrich. B этом отношении важно заметить, что растворимость в воде катализатора на основе марганца зависит от всех вышеперечисленных компонентов катализатора. Например, показано, что моноядерный комплекс марганца, полученный из MnSO₄ и TmTacn, является недостаточно растворимым.where Mn is manganese; L or each L independently represents a multidentate ligand, preferably a cyclic or acyclic compound containing 3 nitrogen atoms; each X independently represents coordinating compounds and each μ-X independently represent bridge coordinating compounds selected from the group consisting of: RO ^- , Cl ^- , Br ^- , I ^- , F ^- , NCS ^- ,

,

NH ₃ , NR ₃ , RCOO ^- ,

,

, OH ^- , O ^2- ,

, HOO ^-, H ₂ ^{O, SH -, CN -,} OCN -, and

and combinations thereof, where R is a C ₁ -C ₂₀ radical selected from the group consisting of alkyl, cycloalkyl, aryl, benzyl, and combinations thereof, and Y is an oxidation-stable counterion. For example, the counterion Y may be an anion selected from the group consisting of RO ^- , Cl ^- , Br ^- , I ^- , F ^- ,

RCOO ^- ,

acetate, tosylate, triflate (CF ₃ SO ₃ ^- ) and combinations thereof, wherein R again represents a C ₁ -C ₂₀ radical selected from the group consisting of alkyl, cycloalkyl, aryl, benzyl and a combination thereof. The type of anion is not very critical, although some anions are more preferred than others. A preferred counterion is

. Ligands applicable to the present invention are acyclic compounds containing at least 7 atoms in the main chain or cyclic compounds containing at least 9 atoms in the cycle, each containing nitrogen atoms separated by at least two carbon atoms. A preferred class of ligands is one based on (substituted) triazacyclononane ("Tacn"). A preferred ligand is 1,4,7-trimethyl-1,4,7-triazacyclononane ("TmTacn"), which is commercially available, for example, from Aldrich. In this regard, it is important to note that the solubility in water of a manganese-based catalyst depends on all of the above components of the catalyst. For example, it was shown that the mononuclear complex of manganese obtained from MnSO ₄ and TmTacn is not sufficiently soluble.

где L и Y имеют значения, указанные, выше, предпочтительно TmTacn в качестве лиганда и PF₆ ^- в качестве противоиона.Binuclear complexes of manganese are more preferred because of their greater activity and solubility in water. Preferred binuclear manganese complexes are those having the formula

wherein L and Y are as defined above, preferably TmTacn as ligand, and PF ₆ ^- as counterion.

According to the present invention, the manganese complex can be used as such or adsorbed on the surface of an insoluble substrate. Illustrative but not limiting examples of such substrates are structured aluminosilicates (e.g. Zeolite A, faujasite and sodalite), amorphous aluminosilicates, silica, alumina, charcoal, microporous polymer resins (for example, polystyrene granules formed by emulsion technology in a highly dispersed phase) clays (especially layered clays, for example hectorite and hydrotalcite). The relative weight ratios of the manganese complex to the substrate can vary from about 10: 1 to about 1: 10000.

The manganese complex is used in catalytically effective amounts. Typically, the catalyst is used in a molar ratio of catalyst (Mn) to allyl chloride in the range from 1:10 to 1: 10000000, preferably from 1:20 to 1: 100000, most preferably from 1:50 to 1: 1000. For convenience, the amount of catalyst can also be expressed in terms of its concentration, given the volume of the aqueous medium. For example, it may be used in a molar concentration (based on Mn) in the range from 0.001 to 10 mmol, preferably from 0.01 to 7 mmol and most preferably from ₀ 01 to 2 mM. In this regard, it is also important to note that epoxidation is of the first order in the concentration of the catalyst and is proportional to the amount of catalyst. As the amount of catalyst increases, the activity increases. However, higher amounts of catalyst must be balanced by its higher cost.

An advantage of the present invention using a water-soluble manganese complex is that the catalyst does not predominantly migrate to the organic phase.

The aqueous reaction medium is usually an aqueous phase containing AC and / or UST and less than 25% by volume, preferably even smaller amounts, if any, of other organic compounds. Although this is not preferred, the reaction medium may contain small amounts of cosolvents, for example, methanol and acetone, and the like. Apart from the presence of AC and / or UST, the aqueous reaction medium accordingly contains at least 90 vol.% Water, preferably 95 vol.%, More preferably 99 vol.%, Even more preferably 99.9 vol.% Water. However, most preferably, the aqueous reaction medium (excluding any amount of AS and / or ESN dissolved in it) is a 100% aqueous phase.

The aqueous reaction medium may contain a buffer system in order to stabilize the pH. For example, it was found that the aqueous reaction medium is well stabilized in the pH range from 2.5 to 8, while the preferred pH range is from 3 to 7 and the most preferred is from 3.5 to 6.5. Therefore, the pH is (much) lower than that used to bleach olefins, usually carried out under more alkaline conditions (for example, at a pH adjusted with NaHCO ₃ to 9.0). A suitable or preferred range can be achieved using several known acid-salt combinations, the preferred combination being based on the oxalic acid-oxalic acid salt system or the acetic acid-acetic acid salt system. When using oxalic acid and sodium oxalate, the pH ratio can vary from 3.7 to 4.2. Typically, this buffer can be used with a molar ratio to catalyst equal to 10: 1, but the amounts can vary within wide limits, for example in the range from 1: 1 to 100: 1.

The aqueous reaction medium may also contain a phase transfer agent and / or surfactant. Known phase transfer agents that can be used in the method of the present invention include quaternary alkylammonium salts. Known surfactants that can be used in the method of the present invention include nonionic surfactants, for example Triton X100 ™, available from Union Carbide.

It is believed that a favorable factor is that the aqueous reaction medium contains at least trace amounts of allyl chloride. Although this is purely a hypothesis, it is believed that due to the presence of allyl chloride, the catalyst remains active, while it is believed that in the absence of allyl chloride and / or in the presence of ESN and / or an oxidizing agent without allyl chloride, the activity of the catalyst decreases.

The conditions for the catalytic oxidation reaction can be easily determined by those skilled in the art. Pressure doesn't really matter. It is believed that the reaction is exothermic, and cooling of the reaction medium may be required. The reaction is preferably carried out at temperatures from about -5 ° C to 30 ° C, preferably from 0 ° C to 20 ° C, and most preferably from 0 ° C to 10 ° C. It should be noted that the reaction product, ESN, is in very small quantities in the aqueous phase. Conversely, an ESN forms an organic phase together with (excess) allyl chloride, if present. Of particular interest in the method of the present invention is that the reaction product, ESN, can form a separate phase. It was shown that with the right choice of reaction conditions, a catalytically effective amount of a water-soluble magnesium complex as an epoxidation catalyst and an aqueous reaction medium, the allyl chloride is converted to ESN, which is then released from the aqueous solution due to limited solubility, forming a product layer or product layers containing ESN which (e) does not contain by-products and does not contain any organic solvents. The product layer, ESN, may contain some unreacted allyl chloride dissolved in it. In fact, there may be two layers containing products that differ in the concentration of allyl chloride and ESN, which therefore can have a higher or lower density compared to the density of the aqueous reaction medium.

To achieve high selectivity and speed in the present invention, the allyl chloride and the oxidizing agent preferably interact with a molar ratio in the range from 1: 0.1 to 1:10, more preferably in the range from 1: 0.2 to 1: 1.2, even more preferably in the range of 1: 0.8 to 1: 1. Allyl chloride is preferably used in an equimolar excess of the oxidizing agent. The amount of reagents should be such that, with the complete conversion of allyl chloride, a larger amount of ESN is formed in comparison with that dissolved in the aqueous reaction medium. Preferably, the amount of reagents should be such that, at 80% conversion of allyl chloride, a larger amount of ESN is formed compared to that dissolved in the aqueous reaction medium. More preferably, the amount of reagents should be such that, at a 50% conversion of allyl chloride, a larger amount of ESN is formed compared to that dissolved in the aqueous reaction medium. This method leads to the production of ESN with a large number of revolutions, with high selectivity with respect to ESN and, in addition, with increased ease of isolation of ESN. To ensure optimal results, reagents must be added to the aqueous phase, and not to the organic phase, which should be formed during the reaction.

As indicated previously, it is considered appropriate that some allyl chloride is present in the aqueous reaction medium. Mixing the organic phase, if present, enriched in allyl chloride, with the aqueous phase may be useful, while back-mixing of the organic phase consisting solely of ESN should preferably be avoided. Therefore, it is believed that stirring or shaking improves the conversion of allyl chloride to ESN, but the ESN itself slows the conversion of allyl chloride. The conversion of allyl chloride ("AC") to epichlorohydrin is discussed below. Depending on the reaction conditions, the reaction can be carried out in a three-layer system containing an organic phase at the bottom and an organic phase at the top. The bottom phase may have a higher density than the reaction medium, for example, due to a relatively higher ESN content, while the organic phase in the upper part has a lower density than the reaction medium, for example, due to a relatively high AS content. However, under the mixing conditions, there is no immediate formation of such separate phases or their occurrence during the reaction, for example, a separate phase (s) can be observed only after the system is at rest. The catalytic oxidation of the present invention is preferably carried out using hydrogen peroxide as an oxidizing agent. Other oxidizing agents can be used, for example, as a precursor of hydrogen peroxide, but in terms of availability and to reduce the negative environmental impact, hydrogen peroxide is the preferred oxidizing agent. Hydrogen peroxide has strong oxidizing properties. As a bleaching agent, it is mainly used for bleaching paper. Usually it is used in an aqueous solution. The concentration of hydrogen peroxide can vary from 15% (for example, when used to bleach hair) to 98% (when used as fuel), at a concentration preferred in industrial use, in the range from 20 to 60%, preferably from 30 to 50% .

In order to ensure optimum oxidative efficiency, the oxidizing agent is preferably added to the aqueous reaction medium at a rate approximately equal to the catalytic oxidation rate.

Catalytic oxidation is carried out using a batch process, a continuous process or a semi-continuous process. In fact, the method can be modified in various ways without changing the essence of the invention.

The catalytic oxidation of allyl chloride will be described below as a general example.

Catalytic oxidation can be carried out in a conventional flow reactor with mixing devices. For example, it may be a conventional paddle mixer operating at a speed of approximately 250 rpm. The catalyst, aqueous reaction medium and reagents may be added at a time or the reagents may be added over a period of time. If hydrogen peroxide is added during the reaction, it is added either to the stirred organic phase containing allyl chloride or to the stirred aqueous reaction medium.

In a semi-continuous process, various recycle streams can be used to control the reaction conditions (maintained at a temperature in the range of -5 ° C to 10 ° C) and to optimize the reaction rate. In the framework of this method, a sedimentation tank may be added to optimize the gravitational separation of the UST. Similarly, a membrane cell can be used to recycle the aqueous reaction medium with reduced catalyst loss.

An example of a material reaction balance according to the method of the present invention:

UST approximately 11000 kg / h

AC approx. 9100 kg / h

H ₂ O ₂ (35%) approximately 6457 kg / hour

H ₂ About 2140 kg / h

As a result of this material balance, the ESN / catalyst ratio is approximately 8000 mol / mol

The following examples will illustrate in more detail individual embodiments of the present invention. All parts, percentages and proportions relating to them and to the attached claims are given by weight, unless otherwise specified.

Examples

Example 1

Catalytic oxidation is carried out using a catalyst of the formula:

In addition, an oxalate / oxalic acid buffer is used containing 35% aqueous hydrogen peroxide as an oxidizing agent and water as an aqueous reaction medium. The experiment is carried out with allyl chloride as the terminal olefin.

experimental part

In a typical epoxidation reaction, 9.3 μmol of catalyst in 50 ml of water, 112.5 μmol of sodium oxalate in 7.5 ml of H ₂ O and 112.5 μmol of oxalic acid in 7.5 ml are placed in a three-necked round-bottomed flask equipped with a mechanical stirrer. H ₂ O. The reaction is started by adding olefin (150 mmol) and a dilute solution of H ₂ O ₂ (200 mmol) at 4 ° C.

An additional 10 ml of water was added as a reaction solvent. An oxidizing agent is added to the reaction solution in flow mode at a rate of 8.8 ml / hour. The pH of the reaction solution is in the range of 3.5 to 3.6, and the stirring speed for most experiments is maintained at 210 rpm using a mechanical stirrer.

Results and discussion

The manganese complex ensures the efficient production of ESN by using water as a solvent. In the epoxidation process using water as a solvent at the beginning of the reaction, the AS is in the form of a separate layer in the upper part of the aqueous catalyst solution. As epoxidation proceeds, the ESN forms a separate phase together with a certain amount of AS dissolved in it. The reaction is carried out several times. Under certain conditions, the reaction system forms three phases from the top to the bottom: the organic, aqueous and second organic phases. At the end of the reaction, both the upper and bottom organic fractions contain significant amounts of ESN and AS. Minor amounts of AS and UST are also found in the water fraction. On the other hand, the system also leads to the formation of a two-layer system with an organic phase (containing ESN and AC) and an aqueous phase.

This example provides a 50% yield of UST calculated on allyl chloride formed with 40% selectivity of hydrogen peroxide, with 7800 TON. No appreciable amounts of diols or other by-products are formed.

Example 2

Various experiments were carried out by the method described in example 1. Table 1 presents the results of epoxidation of AS at various mixing speeds.

Table 1 Epoxidation Speakers: Variation of Mixing Speed No. Reaction time (hour) Mixing Speed (rpm) ESN (mol) TON (for UST) one 6 650 33 3500 2 6 500 36 3900 3 6 210 73 7800 four four 210 64 6900 5 four one hundred 37 3900

This example shows that the yield of the UST increases with decreasing mixing speed until an optimum value is reached.

Example 3, varying the amount of catalyst

The rate of production of UST is proportional to the concentration of catalyst. This example shows that an increase in the amount of catalyst leads to an increase in the yield of ESN.

table 2 EP epoxidation: Varying the amount of catalyst No. Reaction time (hour) The amount of catalyst (μmol) Peroxide Efficiency (%) ESN (mol) Ton one four 4.7 thirty thirty 6400 2 four 9.4 42 64 6900 3 four 18.3 46 66 3600

Example 4, pH effect

In previous experiments, epoxidation reactions were carried out at low pH of about 3.5 to 3.6. Here we showed that the catalyst is active both under acidic and alkaline conditions, that is, at pH = 2.6 in the presence of oxalic acid only, as well as at pH = 8 in the presence of sodium oxalate. These results show that during epoxidation of AS, the catalytic system is active in a wide pH range.

Table 3 The effect of pH on the epoxidation of allyl chloride No. pH Absorbed Peroxide (mol) mmol of the resulting ESN TON ESN Peroxide Selectivity (%) In the organic phase In the water phase one 2.6 55 15.4 7.6 2400 42 2 8 121 29th 19 5000 39

Claims (15)

1. The method of producing epichlorohydrin by the interaction of allyl chloride with an oxidizing agent in the presence of a catalyst in an aqueous reaction medium, followed by removal of the epichlorohydrin product, in which the catalyst contains a water-soluble complex of manganese, and the molar ratio of allyl chloride to oxidizing agent is from 1: 0.1 to 1: 1.2. 2. The method according to claim 1, where the epichlorohydrin product or part thereof is removed as an organic phase that contains an epichlorohydrin product or a mixture of allyl chloride and epichlorohydrin product. 3. The method according to any one of claims 1 or 2, wherein the catalyst contains a manganese mononuclear complex of the general formula (I):

or a binuclear manganese complex of the general formula (II):

where Mn is manganese; L or each L is independently a multidentate ligand; each X independently represents coordinating compounds and each μ-X independently represent bridge coordinating compounds selected from the group consisting of: RO ^- , Cl ^- , Br ^- , I ^- , F ^- , NCS ^- ,

NH ₃ , NR ₃ , RCOO ^- ,

OH ^- , O ^2- ,

HOO ^- , H ₂ O, SH ^- , CN ^- , OCN ^- , and

combinations thereof, where R is a C ₁ -C ₂₀ radical selected from the group consisting of alkyl, cycloalkyl, aryl, benzyl, and combinations thereof, and Y is an oxidation-stable counterion. 4. The method according to claim 3, where each multidental ligand is independently selected from acyclic compounds containing at least 7 atoms in the main chain or cyclic compounds containing at least 9 atoms in the cycle, and each multidental ligand contains 3 nitrogen atoms, separated at least two carbon atoms. 5. The method according to claim 3, where the binuclear manganese complex is used as a catalyst. 6. The method according to claim 1, where the catalyst is used in a molar ratio of catalyst (Mn): allyl chloride in the range from 1:10 to 1: 10000000. 7. The method according to claim 1, where the aqueous reaction medium is the aqueous phase. 8. The method according to claim 1, where the aqueous reaction medium contains a buffer system with a pH in the range from 2.5 to 8.0. 9. The method according to claim 1, where the reaction is carried out at a temperature in the range from -5 ° C to 30 ° C. 10. The method according to claim 1, where the oxidizing agent is hydrogen peroxide. 11. The method according to claim 10, where hydrogen peroxide is used in the form of an aqueous solution in a concentration of from 15% to 98. 12. The method according to claim 1, where the molar ratio of allyl chloride to oxidizing agent is in the range from 1: 0.2 to 1: 1. 13. The method according to claim 1, where the oxidizing agent is added to the aqueous reaction medium at a rate approximately equal to the rate of interaction. 14. The method according to claim 1, where the interaction is carried out using a batch process, a continuous process or a semi-continuous process. 15. The method according to claim 1, where the interaction is carried out on the basis of the following material balance, kg / h:
epichlorohydrin approximately 11000 allyl chloride approximately 9100 H ₂ O ₂ (35%) approximately 6457 H ₂ O approximately 2140